Valve seat structure

ABSTRACT

A valve seat structure includes a cylinder head configured to be mounted at an upper part of a combustion chamber, at least one valve port configured to be formed at a part of the cylinder head being opened and closed by a valve, and a valve seat configured to be mounted along an inner circumferential surface of the valve port, wherein a part of the valve seat is provided with a high hardness material portion made from a high hardness material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2014-0172873, filed on Dec. 4, 2015 with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a valve seat structure, and more particularly, to a valve seat structure capable of improving durability of the valve seat by forming a part of the valve seat from a high hardness material.

BACKGROUND

Generally, an engine is an apparatus which converts heat energy generated by combusting fuel into kinetic energy to generate power. The engine includes a cylinder block and a cylinder head.

The cylinder block forms a frame of the engine and some engine parts are attached to the cylinder block. The cylinder head is positioned at an upper part of the cylinder block and forms a combustion chamber along with the cylinder block. The cylinder head is provided with an intake valve which opens and closes an intake port and an exhaust valve which opens and closes an exhaust port, and ends of the intake and exhaust valves are each provided with valve heads.

For the valve head to completely adhere to the cylinder, an inside of the cylinder head is provided with a valve seat. When the intake port or the exhaust port is opened and closed, the valve head may contact the valve seat to keep the combustion chamber airtight. Therefore, it is possible to prevent gas of the combustion chamber from being leaked and increase heat efficiency.

However, the valve seat is exposed to heat from the combustion chamber, where fuel is ignited. Therefore, the valve seat must include abrasion resistance, impact resistance and heat resistance.

Existing valve seats use a method for coupling all surfaces contacting the valve head with a high hardness material, or existing valve seats use a method for infiltrating cooper into the valve seat, to increase heat conductivity.

However, the method for coupling all surfaces contacting the valve head with a high hardness material may greatly aggravate the heat conductivity of the valve seat since high hardness materials generally have low heat conductivity. As a result, heat transferred to the valve seat is not emitted to the outside. In addition, the high hardness material coupled with all parts contacting the valve head along an inner circumferential surface of the valve seat may increase manufacturing costs of the valve seat.

Further, the method for infiltrating copper into the valve seat may infiltrate a copper component into the contact part of the valve seat to the valve head and lessen the abrasion resistance of the valve seat.

Further, the combustion chamber has a changing temperature depending on position. As the temperature of the combustion chamber is changed depending on position, the temperature of the cylinder head forming the combustion chamber is also changed depending on position. A part of the cylinder head may generate relatively higher heat and other parts thereof may generate relatively lower heat.

Further, like the cylinder head, the valve seat mounted in the cylinder head has different temperatures depending on the position. Therefore, a part of the valve seat having temperature relatively higher than that of other parts may be thermally deformed, the valve seat may not completely adhere to the valve head due to a part of the thermally deformed valve seat, and gas may be leaked between the valve seat and the valve head. This may cause a deterioration in the engine power or the damage of the engine.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY OF THE DISCLOSURE

The present disclosure has been made in an effort to provide a valve seat structure in which a part of the valve seat higher than a predetermined temperature is formed from a high hardness material and to facilitate an assembly of the valve seat.

An exemplary embodiment of the present disclosure provides a valve seat structure, including: a cylinder head configured to be mounted at an upper part of a combustion chamber; at least one valve port configured to be formed at a part of the cylinder head to be opened and closed by an intake valve or an exhaust valve; and a valve seat configured to be mounted along an inner circumferential surface of the valve port, wherein a part of the valve seat is provided with a high hardness material portion made from a high hardness material and the high hardness material portion is formed only at a high-temperature part of the valve seat.

The high hardness material portion may exhibit bilateral symmetry based on a straight line passing through centers of a spark plug and a valve port as an axis.

A central angle of the fan-shaped arc may range from 10° to 350°.

The high hardness material portion may be made from one material.

The high hardness material portion may be made from at least one material and the high hardness material may be formed at a location contacting the valve.

The high hardness material portion may be made from one material into which a copper component is infiltrated.

The high hardness material portion may be made from at least one material and the high hardness material may be formed at a location contacting the valve and the inside thereof may be infiltrated with the copper component.

The high hardness material portion may include a coupling portion from which the portion protrudes, the cylinder head may have a part provided with a groove-shaped mounting portion corresponding to the coupling portion, and the coupling portion and the mounting portion may be coupled with each other.

The high hardness material portion may have a part provided with a groove-shaped coupling portion, the cylinder head may have a part provided with a protrusion-shaped mounting portion corresponding to the coupling portion, and the coupling portion and the mounting portion may be coupled with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a valve seat structure according to an exemplary embodiment of the present disclosure.

FIG. 2 is a perspective view of a valve seat according to an exemplary embodiment of the present disclosure.

FIG. 3 is an enlarged view of part “A” of FIG. 2.

FIG. 4 is a partial perspective view of a cylinder head in which the valve seat according to the exemplary embodiment of the present disclosure is mounted.

FIG. 5 is a front view of the general cylinder head in which the valve seat is mounted.

FIG. 6 is a temperature distribution graph of the valve seat of FIG. 5.

FIG. 7 is a perspective view of a valve seat according to another exemplary embodiment of the present disclosure.

FIG. 8 is a partial perspective view of a cylinder head in which the valve seat according to the exemplary embodiment of the present disclosure is mounted.

DETAILED DESCRIPTION

In the following detailed description, only certain exemplary embodiments of the present disclosure have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present disclosure.

Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

Throughout the specification, like reference numerals designate like elements throughout the specification.

An exemplary embodiment of the present disclosure will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a valve seat structure according to an exemplary embodiment of the present disclosure, FIG. 2 is a perspective view of a valve seat according to an exemplary embodiment of the present disclosure, FIG. 3 is an enlarged view of part “A” of FIG. 2, and FIG. 4 is a partial perspective view of a cylinder head in which the valve seat according to the exemplary embodiment of the present disclosure is mounted.

As illustrated in FIG. 1, the valve seat structure according to the exemplary embodiment of the present disclosure includes a cylinder head 5, a valve port 7, and a valve seat 100.

The cylinder head 5 is mounted at an upper part of the combustion chamber and forms a part of the combustion chamber along with the cylinder block. The cylinder head 5 is provided with a spark plug 30 which ignites mixed gasses in the combustion chamber. The cylinder head 5 includes at least one valve port 7.

The valve port 7 may be formed in a shape such that it is opened at a lower part of the cylinder head 5. Intake or exhaust may communicate with the combustion chamber through the valve port 7. An inside of the valve port 7 is provided with a valve (not illustrated). The valve may reciprocate at an appropriate timing to control a flow of liquid or gas. The valve port 7 may be opened and closed by the reciprocation of the valve. That is, the valve may supply a mixture of air and fuel into the combustion chamber or emit exhaust gas from the combustion chamber, while opening the valve port 7 and may prevent the mixture or the exhaust gas from being leaked while sealing the valve port 7.

The valve seat 100 may serve to maintain an airtight seal while contacting the valve, as the valve seals the valve port 7. The valve seat 100 may be mounted along the inner circumferential surface of the valve port 7. The valve seat 100 may encounter heat generated by ignited fuel in the combustion chamber or supplied with heat through contacting the valve. Therefore, the valve seat 100 may have a higher temperature at a surface contacting the valve than that at a surface coupled with the valve port 7.

Meanwhile, the combustion chamber may have a difference in temperature depending on the position, and the cylinder head 5 covering the combustion chamber may have a different temperature depending on the position. Further, the valve seat 100 temperature may also depend on the position. Specifically, the temperature of the valve seat 100 positioned near the ignition plug 30 may be relatively higher than that of other parts. This phenomenon will be described in more detail with reference to FIGS. 5 and 6.

FIG. 5 is a front view of the general cylinder head in which the valve seat is mounted and FIG. 6 is a temperature distribution graph of the valve seat of FIG. 5.

As illustrated in FIG. 5, a horizontal axis of the temperature distribution graph 200 represents a distance from positions B1, C1, D1, and E1 of the valve seat to a center C of the valve portion and a vertical axis thereof represents the temperature of the valve seat 100 corresponding to each position. According to the temperature distribution graph 200, the temperature of the valve seat 100 which is positioned on a straight line B1-C connecting between a center 31 of the spark plug and the center C of the valve port is highest. Further, according to the drawings, the temperature of the valve seat 100 positioned on straight lines C1-C and D1-C near the center 31 of the spark plug is also relatively high. Further, the temperature of the valve seat 100 positioned on the straight line E1-C farthest away from the spark plug is relatively low.

The valve seat structure according to the exemplary embodiment of the present disclosure include a high hardness material portion 10 of the high hardness material formed at a part of the valve seat 100 that experiences more than a predetermined temperature to prevent a part of the high-temperature valve seat 100 from being thermally deformed. As described above, the part where the temperature of the valve seat 100 is relatively high is positioned on the straight line B1-C connecting between the center of the spark plug 30 and the center C of the valve port 7. Therefore the high hardness material portion 10 is preferably installed to face the spark plug 30.

The parts other than the high hardness material portion 10 of the valve seat 100 may be provided with a general material portion 20 of a general hardness material.

As such, only a part of the valve seat 100 is made from the high hardness material to reduce the composition ratio of the high hardness material. Further, the heat conductivity of the valve seat 100 may be improved and costs may be saved.

The high hardness material portion 10 may be formed to exhibit bilateral symmetry based on a straight line passing through the centers 31 and C of the spark plug as an axis. Further, the high hardness material portion 10 may be formed in a fan-shaped arc and a central angle X of the fan-shaped arc preferably ranges from 10° to 350° but is not limited thereto.

Meanwhile, the whole of the high hardness material portion 10 may be made of one material. Further, only a part contacting the high-temperature valve may be made from the high hardness material and thus the cross section thereof may be made from two kinds of materials. Further, the high hardness material portion 10 may be made from one high hardness material into which the copper component is infiltrated. Further, only a part contacting the valve may be made from the high hardness material and the inside thereof may be infiltrated with the copper component.

The high hardness material portion 10 may include a coupling portion 50. As illustrated in FIGS. 3 and 4, the coupling portion 50 may be formed to have a protrusion shape which protrudes from an upper part of the high hardness material portion 10. In this case, the cylinder head 4 may be provided with a groove-shaped mounting portion 55 corresponding to the coupling portion 50 and the coupling portion 50 may be coupled by the mounting portion 55. As such, the coupling portion 50 may be mounted in the mounting portion 55 and thus the valve seat 100 may be easily assembled in a direction in which the high hardness material portion 10 faces the spark plug 30.

FIG. 7 is a perspective view of a valve seat according to another exemplary embodiment of the present disclosure and FIG. 8 is a partial perspective view of a cylinder head in which the valve seat, according to another exemplary embodiment of the present disclosure, is mounted.

According to another exemplary embodiment of the present disclosure, as illustrated in FIGS. 7 and 8, the coupling portion 60 may have a groove shape at the upper part of the high hardness material portion 10. When the coupling portion 60 has the groove shape, the mounting portion 65 has a protruding shape and thus may be coupled with the coupling portion 60.

As described above, according to the exemplary embodiment of the present disclosure, only the part that experiences more than a predetermined temperature in a part of the valve seat may be made from the high hardness material, thereby providing the valve seat in which the composition ratio of the high hardness material is minimized. Therefore, the durability of the valve seat is kept as it is and the cost may be saved. Further, the composition ratio of the high hardness material having the low heat conductivity is reduced and thus the heat conductivity of the valve seat may be improved.

Further, it may be possible to prevent the valve seat from being damaged due to the temperature deviation by constantly maintaining the temperature distribution of the valve seat.

Additionally, the mounting groove and the mounting protrusion may be formed at a part of the valve seat made from the high hardness material. As a result, the valve seat may be easily assembled with the cylinder head.

While this disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. While this disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A valve seat structure, comprising: a cylinder head mounted at an upper part of a combustion chamber; at least one valve port formed at a part of the cylinder head being opened and closed by a valve; and a valve seat mounted along an inner circumferential surface of the valve port, wherein a part of the valve seat is provided with a high hardness material portion made from a high hardness material.
 2. The valve seat structure of claim 1, wherein the valve is an exhaust valve.
 3. The valve seat structure of claim 1, wherein the valve is an intake valve.
 4. The valve seat structure of claim 1, wherein the high hardness material portion is formed in a fan-shaped arc and is positioned to face a spark plug.
 5. The valve seat structure of claim 4, wherein a central angle of the fan-shaped arc ranges from 10° to 350°.
 6. The valve seat structure of claim 5, wherein the high hardness material portion is made from one material.
 7. The valve seat structure of claim 5, wherein the high hardness material portion is made from at least one material including a high hardness material and the high hardness material is formed at a portion contacting the valve.
 8. The valve seat structure of claim 5, wherein the high hardness material portion is made from one material into which a copper component is infiltrated.
 9. The valve seat structure of claim 5, wherein the high hardness material portion is made from at least one material including a high hardness material and the high hardness material is positioned in an inner side of the valve seat contacting the valve and the inside thereof is infiltrated with a copper component.
 10. The valve seat structure of claim 1, wherein the high hardness material portion includes a coupling portion having a protruding shape, the cylinder head has a part provided with a groove-shaped mounting portion corresponding to the coupling portion, and the coupling portion and the mounting portion are coupled with each other.
 11. The valve seat structure of claim 1, wherein the high hardness material portion has a part provided with a groove-shaped coupling portion, the cylinder head has a part provided with a protrusion-shaped mounting portion corresponding to the coupling portion, and the coupling portion and the mounting portion are coupled with each other. 